Wear-resistant, superabrasive compacts are utilized in a variety of mechanical applications. For example, polycrystalline diamond compacts (“PDCs”) are used in drilling tools (e.g., cutting elements, gage trimmers, etc.), machining equipment, bearing apparatuses, wire-drawing machinery, and in other mechanical apparatuses.
PDCs have found particular utility as superabrasive cutting elements in rotary drill bits, such as roller cone drill bits and fixed-cutter drill bits. A PDC cutting element typically includes a superabrasive diamond layer commonly referred to as a diamond table. The diamond table may be formed and bonded to a substrate using a high-pressure, high-temperature (“HPHT”) process. The PDC cutting element may also be brazed directly into a preformed pocket, socket, or other receptacle formed in a bit body of a rotary drill bit. The substrate may often be brazed or otherwise joined to an attachment member, such as a cylindrical backing. A rotary drill bit typically includes a number of PDC cutting elements affixed to the bit body. A stud carrying the PDC may also be used as a PDC cutting element when mounted to a bit body of a rotary drill bit by press-fitting, brazing, or otherwise securing the stud into a receptacle formed in the bit body.
Conventional PDCs are normally fabricated by placing a cemented carbide substrate into a container with a volume of diamond particles positioned adjacent to the cemented carbide substrate. A number of such cartridges may be loaded into an HPHT press. The substrates and volume of diamond particles are then processed under HPHT conditions in the presence of a catalyst material that causes the diamond particles to bond to one another to form a matrix of bonded diamond grains defining a polycrystalline diamond (“PCD”) table that is bonded to the substrate. The catalyst material is often a metal-solvent catalyst (e.g., cobalt, nickel, iron, or alloys thereof) that is used for promoting intergrowth of the diamond particles. For example, a constituent of the cemented carbide substrate, such as cobalt from a cobalt-cemented tungsten carbide substrate, liquefies and sweeps from a region adjacent to the volume of diamond particles into interstitial regions between the diamond particles during the HPHT process. The cobalt acts as a catalyst to promote intergrowth between the diamond particles, which results in formation of bonded diamond grains.
Because of different coefficients of thermal expansion and modulus of elasticity between the PCD table and the cemented carbide substrate, residual stresses of varying magnitudes may develop within different regions of the PCD table and the cemented carbide substrate. Such residual stresses may remain in the PCD table and cemented carbide substrate following cooling and release of pressure from the HPHT process. These complex stresses may be concentrated near the PCD table/substrate interface. Residual stresses at the interface between the PCD table and cemented carbide substrate may result in premature failure of the PDC upon cooling or during subsequent use under thermal stresses and applied forces.
In order to help reduce de-bonding of the PCD table from the cemented carbide substrate, some PDC designers have made the interfacial surface of the cemented carbide substrate that bonds to the PCD table significantly nonplanar. For example, various nonplanar substrate interfacial surface configurations have been proposed and/or used, such as a plurality of spaced protrusions, a honeycomb-type protrusion pattern, and a variety of other configurations.